Colorimetric and spectroradiometric characteristics of narrow-field-of-view clear skylight in Granada, Spain.
- J. Hernández-Andrés, J. Romero, R. L. Lee
- PhysicsJournal of The Optical Society of America A…
- 1 February 2001
A principal-components analysis shows that three vectors are required for accurate clear-sky colorimetry, whereas six are needed for spectral analyses, and routinely observe that sky color and luminance are asymmetric about the solar meridian.
Color and spectral analysis of daylight in southern Europe.
- J. Hernández-Andrés, J. Romero, J. Nieves, R. L. Lee
- PhysicsJournal of The Optical Society of America A…
- 1 June 2001
The principal-components analysis shows that Granada daylight spectra can be adequately represented by using six-dimensional linear models in the visible, whereas seven-dimensional models are required if the authors include the UV or near-IR.
Polarization singularities in the clear sky
- M. Berry, Michael Robert Dennis, R. L. Lee
- Physics
- 1 November 2004
Ideas from singularity theory provide a simple account of the pattern of polarization directions in daylight. The singularities (two near the Sun and two near the anti-Sun) are points in the sky…
Digital imaging of clear-sky polarization.
- R. L. Lee
- PhysicsApplied Optics
- 20 March 1998
If digital images of clear daytime or twilight skies are acquired through a linear polarizing filter, they can be combined to produce high-resolution maps of skylight polarization that consistently show that the familiar Arago and Babinet neutral points are part of broader areas in which skylights polarization is often indistinguishably different from zero.
Calculating correlated color temperatures across the entire gamut of daylight and skylight chromaticities.
- J. Hernández-Andrés, R. L. Lee, J. Romero
- PhysicsApplied Optics
- 20 September 1999
Chromaticities calculated from the measurements of nearly 7000 daylight and skylight spectra are used to test an equation that accurately maps CIE 1931 chromaticities x and y into CCT, and this equation is accurate across wide chromaticity and CCT ranges (3000-10(6) K) spanned by daylight andSkylight.
What are "all the colors of the rainbow"?
- R. L. Lee
- ArtApplied Optics
- 20 August 1991
Digital image analysis of color slides shows that the natural rainbow's colors are not especially pure and that the bow's background causes much of this desaturation.
Mie theory, airy theory, and the natural rainbow.
- R. L. Lee
- PhysicsApplied Optics
- 20 March 1998
Compared with Mie scattering theory, Airy rainbow theory clearly miscalculates some monochromatic details of scattering by small water drops, yet when monodisperse Airy theory is measured by perceptual standards such as chromaticity and luminance contrast, it differs very little from Mie theory.
Twilight and daytime colors of the clear sky.
- R. L. Lee
- Environmental Science, PhysicsApplied Optics
- 20 July 1994
Digital image analysis of the cloudless sky's daytime and twilight chromaticities challenges some existing ideas about sky colors. First, although the observed colors of the clear daytime sky do lie…
Horizon brightness revisited: measurements and a model of clear-sky radiances.
- R. L. Lee
- Environmental Science, PhysicsApplied Optics
- 20 July 1994
Spectroradiometry and digital image analysis confirm this near-horizon radiance maximum's reality, and they show that its angular width and elevation vary with solar elevation, azimuth relative to the Sun, and aerosol optical depth.
DRIVER VISIBILITY UNDER WET PAVEMENT CONDITIONS: SIZE, SHAPE AND SPACING OF OBJECT MARKERS/DELINEATORS. FINAL REPORT
- R. L. Lee, R. Hostetter, H. Leibowitz
- Mathematics
- 1 September 1991
This study sought to reduce the risks of wet, nighttime driving by determining the minimum visibility required of roadway delineators. To isolate the contributions that discrete delineators have on…